Amine salt of lignan compound

ABSTRACT

The present invention provides an amine salt of a lignan compound, i.e., [1-O-[4-(3,4-dimethoxyphenyl)-2-(3- ethylpentanoyl)-5,6,7-trimethoxy-3- (methoxycarbonyl)naphthalen-1-yl]-beta-D- glucopyranoside]uronic acid, which is useful as a medicament. The present invention also provides a method for purifying said lignan compound.

TECHNICAL FIELD

[0001] The present invention relates to an amine salt of a lignan compound.

BACKGROUND ART

[0002] A lignan compound represented by formula I:

[0003] wherein,

[0004] R⁰ is a hydrogen or a hydrophilic group;

[0005] R¹ is a lower alkyl group which may be substituted, a cycloalkyl group which may be substituted, a cycloalkyl lower alkyl group which may be substituted, an aryl group which may be substituted, an aralkyl group which may be substituted, a heterocycle which may be substituted;

[0006] R′ is a lower alkyl group which may be substituted or an aralkyl group which may be substituted; and

[0007] R⁴, R⁵, R⁶, R⁷ and R⁸ are each a lower alkyl group and salts thereof are known to be useful in various clinical uses, particularly, as an antihyperlipidemia drug or a bile acid reabsorption inhibiting drug (Japanese Patent Publication (not examined) No. 241206/1997). The present inventors have found that a lignan compound represented by the following formula II, which is a member of the above formula I, is particularly useful as a medicament. However, this compound is not crystalline, and therefore, in an industrial production thereof, it has been necessary to conduct column chromatography for several times in order to purify the compound. Moreover, the yield of the compound has been low for this reason. The above Japanese Patent Publication (not examined) No. 241206/1997 does not describe an amine salt in terms of a salt of a compound of formula I.

PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In an industrial mass production aiming at use as a medicament of the compound represented by formula II:

[0009] i.e., [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid (glucuronate conjugate), it was very inconvenient that column chromatography had to be conducted in order to purify the compound, and therefore, development of a simple method for the purification of the compound has been desired.

MEANS TO SOLVE THE PROBLEMS

[0010] As a result of research for the purification of the compound of formula II, the present inventors have found that this compound can be crystallized by transforming into an amine salt thereof, and here, succeeded in purifying this compound efficiently by such crystallization. The present invention has been accomplished by this discovery. By transforming into an amine salt to be crystallized, the compound of formula II can be refined and easily isolated from a reaction mixture by means such as filtration. The amine salt of said compound isolated can be transformed easily into the free compound by treating with a dilute acid or the like.

[0011] Thus, the present invention provides

[0012] (1) An amine salt of [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid;

[0013] (2) The amine salt of (1) which is a diethylamine salt;

[0014] (3) The amine salt of (1) or (2) which is a crystal;

[0015] (4) The diethylamine salt of (3) which exhibits a powder X-ray diffraction pattern wherein the main peaks appear at 2θ=9.800, 13.760, 16.960, 17.100, 18.140 and 18.340 (degree);

[0016] (5) The diethylamine salt of (4) which exhibits a powder X-ray diffraction pattern wherein the main peaks appear at 2θ=8.820, 9.800, 13.760, 14.340, 14.540, 15.560, 16.960, 17.100, 18.140, 18.340, 19.560, 21.740, 22.040 and 22.280 (degree);

[0017] (6) A process for preparing [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid, which comprises purification thereof by transforming the acid into an crystalline amine salt;

[0018] (7) The process of (6) wherein said process does not comprise a treatment by means of column chromatography;

[0019] (8) A process for preparing [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid, which comprises a treatment of a crystalline amine salt thereof to form the free compound; and

[0020] (9) A pharmaceutical composition comprising the amine salt of any one of (1)-(5).

[0021] For preparation of the amine salt of the invention, a crude product of the compound of formula (II) is dissolved in an appropriate solvent, for example, alcoholic solvents such as methanol, ethanol, or isopropyl alcohol, ether solvents such as THF, aromatic hydrocarbons such as toluene, or xylene. The resultant mixture is added with an amine to mix at a temperature between 0° C. and 100° C., preferably between room temperature and 70° C., and then optionally allowed to cool to a temperature between room temperature and 0° C. Crystals precipitated can be filtered out and washed with a solvent as described above. Diethylamine is preferable for use as an amine.

[0022] As described above, the resultant amine salt of the compound of formula II, can be treated easily with an acid, such as a dilute acid, to form the free compound.

[0023] As described above, the amine salt of the invention is useful as an intermediate, but itself may be used as an active ingredient. Accordingly, the present invention further provides a medicament, such as anti-hyperlipidemia drug, containing said amine salt. The amine salt of the invention may be a solvate, such as a hydrate or an alcoholate.

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] The following examples further illustrate the present invention and are not intended to be limiting to the scope of the invention in any respect.

Example 1 Step 1

[0025]

[0026] Under nitrogen stream, 2.58 g of Silver(I) Carbonate was added to a solution in quinoline (27 mL) of 3.00 g (5.56 mmol) of Compound 1, which is described in Example 1 of Japanese Patent Publication (not examined) No. 310634/1993, and the mixture was stirred for 42 minutes under room temperature. To the resultant reaction mixture, 3.53 g (8.89 mmol) of Bromide 2 was added, and the mixture was stirred for 20 hours. Then, ice, 6 N hydrochloric acid (40 mL) and ethyl acetate were added, and the mixture was filtrated. The filtrate was extracted with ethyl acetate, and the extract was washed with water, saturated sodium bicarbonate solution and brine, and dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure to yield 5.0 g of a crude product of Compound 3. The resultant product was used in the next reaction without further purification.

[0027] Rf: 0.22 (n-hexane:EtOAc=1:1, SiO₂TLC)

Step 2

[0028]

[0029] The crude product of Compound 3 obtained above (5.0 g) was dissolved in methanol (50 mL), added with 60% sodium hydride (145 mg) under ice cooling, and the resultant mixture was allowed to warm to room temperature with stirring for two hours. Saturated aqueous solution of ammonium chloride (2 mL) was added to the mixture, and methanol was removed under reduced pressure. To the residue, water was added and the mixture was extracted with ethyl acetate. The extract was washed with water and brine, and dried over anhydrous magnesium sulfate. Solvent was removed under reduced pressure to yield 4.2 g of a residue. The residue (4.2 g) was dissolved in methanol (120 mL), added with aqueous solution of lithium carbonate (prepared from. 425 mg of lithium carbonate and 60 mL of water) under ice cooling. The resultant mixture was allowed to warm to room temperature with stirring for three days. Solvent was removed under reduced pressure. To the residue, 1 N hydrochloric acid (13.5 mL) was added under ice cooling, adjusted the pH to 4, and the mixture was extracted with ethyl acetate. The extract was washed with water and brine, and dried over anhydrous magnesium sulfate. Solvent was removed under reduced pressure to yield 3.1 g of a crude product of Compound 4. The resultant product was used in the next reaction without further purification.

[0030] Rf: 0.27 (toluene:CH₃CN:AcOH:n-BuOH=10:10:1:1, SiO₂TLC)

Step 3

[0031]

[0032] The crude product of Compound 4 obtained above (3.1 g) was dissolved in isopropyl alcohol (40 mL), and diethylamine (0.63 mL) was added to the solution at 50° C., and the resultant mixture was allowed to cool to room temperature with stirring for 1 hour. Precipitated crystals were filtered out, washed with isopropyl alcohol for three times to yield 2.57 g of the desired Compound 5 (59% in three steps). mp: 205-206° C. (dec) ¹H NMR: δ (DMSO-d₆) 0.78-0.85 (m, 6H), 1.12 (t, J=7.2 Hz, 6H), 1.21-1.38 (m, 4H), 1.78-1.84 (m, 1H), 2.83 (q, J=7.2 Hz, 4H), 2.99-3.80 (m, 22H), 3.95 (s, 3H), 4.74 (d like, 1H), 5.13 (br.s, 1H), 5.83-6.00 (m, 1H), 6.59-6.93 (m, 3H), 8.13 & 8.14 (each s, total 1H). IR: ν (CHCl₃) 3587, 3170, 3008, 2964, 1722, 1682, 1608, 1516, 1464, 1414, 1352, 1240, 1138, 1066. Anal. Calcd. for C₄₀H₅₅NO₁₅: C, 60.82; H, 7.02; N, 1.77: Calcd. for C₄₀H₅₅NO₁₅·3/10H₂O: C, 60.41; H, 7.05; N, 1.76. Found: C, 60.23; H, 7.01; N, 2.04. Karl Fisher Calcd. for C₄₀H₅₅NO₁₅·3/10H₂O: H₂O, 0.68. Found: H₂O, 0.68.

[0033] X-ray diffraction pattern of Compound 5 was as shown bellow. TABLE 1 Half Value Relative 2θ Breadth d value Intensity Intensity 6.820 0.118 12.9501 80 7 7.340 0.141 12.0338 102 9 8.500 0.188 10.3940 495 43 8.820 0.259 10.0176 580 50 9.800 0.306 9.0179 982 85 10.200 0.141 8.6651 435 37 10.840 0.141 8.1549 130 11 11.080 0.118 7.9788 135 12 12.280 0.165 7.2017 230 20 12.840 0.118 6.8888 160 14 13.760 0.188 6.4302 970 83 14.340 0.141 6.1714 650 56 14.540 0.141 6.0870 695 60 15.360 0.235 5.7638 530 46 15.560 0.165 5.6902 705 61 16.400 0.118 5.4006 340 29 16.960 0.188 5.2235 1005 86 17.100 0.259 5.1811 1092 94 18.140 0.235 4.8863 1162 100 18.340 0.141 4.8335 982 85 18.740 0.118 4.7312 492 42 19.560 0.165 4.5347 678 58 20.200 0.118 4.3924 320 28 21.140 0.118 4.1992 382 33 21.740 0.118 4.0846 625 54 22.040 0.141 4.0297 675 58 22.280 0.212 3.9868 632 54 23.560 0.141 3.7730 382 33 24.140 0.141 3.6837 415 36 24.360 0.118 3.6509 282 24 25.420 0.118 3.5010 288 25 25.680 0.141 3.4662 270 23 25.840 0.118 3.4451 282 24 26.840 0.118 3.3189 298 26 27.060 0.118 3.2924 308 26 27.700 0.141 3.2178 280 24 27.880 0.141 3.1974 268 23 28.160 0.141 3.1663 288 25 28.380 0.165 3.1422 205 18 28.760 0.118 3.1016 268 23 29.120 0.118 3.0640 308 26 29.260 0.118 3.0497 362 31 29.680 0.118 3.0075 242 21 31.220 0.165 2.8626 248 21 32.020 0.118 2.7928 230 20 33.160 0.118 2.6994 200 17 38.380 0.141 2.3434 225 19 38.520 0.118 2.3352 135 12

[0034] Conditions for the X-ray diffraction analysis

[0035] Model: RIGAKU DENKISYA RAD-IIC Powder X-ray Diffraction meter

[0036] X-ray: CuK-ALPHA1/40 kV/40 mM

[0037] Goniometer: wide-angle goniometer

[0038] Attachment: rotating stage (reflection method)

[0039] Filter: none

[0040] Counter monochrome meter: curved crystal monochrome meter

[0041] Divergence slit: 0.5°

[0042] Scattering slit: 0.5°

[0043] Receiving slit: 0.3 mm

[0044] Counter: scintillation counter

[0045] Scanning mode: continuous

[0046] Scanning speed: 3°/min

[0047] Scanning step: 0.02°

[0048] Scanning axis: 2θ/θ

[0049] Scanning range: 5-40°

[0050] θ offset: 0°

[0051] Fixed angle: 0°

[0052] Cuvette: 5 mm Φ

Step 4

[0053]

[0054] Compound 5 obtained above (1.00 g, 12.7 mmol) was added with ethyl acetate (30 mL) and water (30 mL), and the pH was adjusted to 4.0 by addition of 0.1 N hydrochloric acid. The reaction mixture was extracted with ethyl acetate, washed with saturated aqueous solution of sodium chloride, and dried over anhydrous sodium sulfate. Solvent was removed under reduced pressure, and the resultant residue was dissolved in ether (40 mL), and solvent was removed again under reduced pressure. The residue was powdered from ether/n-pentane to give 806 mg (87%) of the desired Compound 4 as an amorphous material. ¹HNMR: δ(DMSO-d₆) 0.81 (t, J=7.5 Hz, 3H), 0.88 (t, J=7.5 Hz, 3H), 1.18-1.41 (m, 4H), 1.78-1.89 (m, 1H), 2.69-2.80 (m, 1H), 3.17-3.80 (m, 20H), 3.96 (s, 3H), 4.71 (t like, 1H), 5.34 (br.s, 1H), 5.36 (d like, 1H), 6.19 & 6.23 (each d, J=5.1 Hz, total 1H), 6.57-6.95 (m, 3H), 8.17 (s, 1H), 12.60 (br.s, 1H). IR: ν (CHCl₃), 3591, 3483, 3327, 2964, 1743, 1697, 1608, 1516, 1464, 1415, 1352, 1242, 1138, 1095, 1065, 1030.

Reference Example 1

[0055] X-ray diffraction pattern of Compound 1 was as shown bellow. The conditions used were the same as in Example 1. TABLE 2 Half Value Relative 2θ Breadth d value Intensity Intensity 6.520 0.165 13.5453 392 21 7.360 0.165 12.0011 1780 96 10.540 0.282 8.3864 555 30 12.060 0.212 7.3326 1338 72 12.400 0.188 7.1323 540 29 13.080 0.235 6.7630 338 18 14.580 0.118 6.0704 212 12 15.060 0.329 5.8780 335 18 16.340 0.188 5.4203 635 34 17.560 0.141 5.0464 358 19 18.260 0.212 4.8545 372 20 19.740 0.165 4.4937 478 26 20.960 0.165 4.2348 295 16 21.640 0.118 4.1033 548 30 22.280 0.235 3.9868 412 22 22.940 0.212 3.8736 1845 100 23.480 0.212 3.7857 752 41 24.380 0.212 3.6480 1292 70 25.880 0.118 3.4398 410 22 26.260 0.259 3.3909 355 19 26.600 0.118 3.3483 218 12 26.700 0.118 3.3360 185 10 27.040 0.118 3.2948 245 13 27.140 0.118 3.2829 220 12 27.460 0.165 3.2454 170 9 28.240 0.188 3.1575 380 21 28.500 0.165 3.1293 290 16 28.940 0.141 3.0827 148 8 29.460 0.165 3.0294 302 16 30.020 0.141 2.9742 128 7 30.980 0.141 2.8842 190 10 31.160 0.118 2.8679 165 9 31.780 0.118 2.8134 182 10 32.620 0.118 2.8134 178 10 38.420 0.212 2.3411 470 25 39.060 0.141 2.3042 128 7

EFFECT OF THE INVENTION

[0056] The present invention enables simple purification of the compound which is useful as a medicament, i.e., [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid, by transforming said compound into an amine salt thereof to be crystallized, and thus has opened the way to use this compound as a medicament. Furthermore, the present invention has improved drastically the total yield of this compound from Compound 1. 

1. An amine salt of [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid.
 2. The amine salt of claim 1 which is a diethylamine salt.
 3. The amine salt of claim 1 or claim 2 which is a crystal.
 4. The diethylamine salt of claim 3, which exhibits a powder X-ray diffraction pattern wherein the main peaks appear at 2θ=9.800, 13.760, 16.960, 17.100, 18.140 and 18.340 (degree).
 5. The diethylamine salt of claim 4, which exhibits a powder X-ray diffraction pattern wherein the main peaks appear at 2θ=8.820, 9.800, 13.760, 14.340, 14.540, 15.560, 16.960, 17.100, 18.140, 18.340, 19.560, 21.740, 22.040 and 22.280 (degree).
 6. A process for preparing [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid, which comprises purification thereof by transforming the acid into an crystalline amine salt.
 7. The process of claim 6, wherein said process does not comprise a treatment by means of column chromatography.
 8. A process for preparing [1-O-[4-(3,4-dimethoxyphenyl)-2-(3-ethylpentanoyl)-5,6,7-trimethoxy-3-(methoxycarbonyl)naphthalen-1-yl]-beta-D-glucopyranoside]uronic acid, which comprises a treatment of a crystalline amine salt thereof to form the free compound.
 9. A pharmaceutical composition comprising the amine salt of any one of claims 1 to
 5. 